The safety and quality of many perishable goods such as food, drugs, vaccines and blood, depend mainly on appropriate handling during distribution and storage. Different factors such as gas composition, relative humidity and temperature affect the effective lifetime of perishable goods. Of all storage aspects, temperature abuse is the most frequently observed factor for deterioration, based on diverse physical, chemical, enzymatic or microbial processes.
Time temperature indicators (alternatively called “Time temperature integrators”) are devices (typically labels) with changeable observable physical property in a rate that is proportional to the temperature and time, and thus provide an indication of the full time-temperature history of their immediate surroundings. When attached to a perishable good, a TTI (appropriately designed and calibrated) monitors its time-temperature history and provides a simple, usually visual, indication of its freshness condition.
One example of a TTI is disclosed in U.S. Pat. No. 4,737,463. Another example is the TTI developed in part by the one inventor of the present invention and described in WO 99/39197.
U.S. Pat. No. 6,009,400 discloses a method and arrangement for alerting customers from purchasing perished items using bar codes with changeable properties when subjected to factors causing perishability. This technique is aimed at preventing retail establishment customers from unwittingly purchasing perishable items that may have been adversely affected by being subjected to at least one predetermined factor. This is achieved by providing an identification object, such as a label, tag or packaging material, with an initially machine-scannable bar code of such a character that its scannability is at least gravely impaired when the identification object is subjected to the predetermined factor. The identification object is secured to the respective item for both of them to be subsequently exposed to the same conditions such that a failed scan of the bar code occurring at the time of purchase alerts the customer to a previous occurrence among such conditions of the predetermined factor that may have adversely affected the item being purchased. In another aspect, a non-readable bar code is rendered readable by exposure to the predetermined factor, thereby alerting the customer.